There was a website dji-innovations.com but they no longer support the v1.1 any more.Is it the transmitter that's beeping?
I don't know much more than this manual gives. But I think it's a low battery alarm so the battery might be going bad if it's old you only get about 15 minutes on a good hot battery!
But I have never heard mine doing an alarm but that's where I would start. Let us know!!